JPH11346308A - Image reader for transparent original - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image reader for a transparent original that detects a foreign material on a transparent original at a high speed with high precision regardless of a simple configuration consisting of a single optical system. SOLUTION: The reader is provided with an image read means 1 that reads an image on a transparent original as image data corresponding to each pixel, a frame memory 2 that stores the image data read by the image read means 1, and a foreign material detection means 3 that detects image data having a signal level corresponding to a density of the transparent original within a prescribed range as abnormity data among the image data stored in the frame memory 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an image reading apparatus for a transparent original.

[0002]

2. Description of the Related Art A film scanner for reading an image on a film is known as one of image reading apparatuses for a transparent original. In such a film scanner, when there is a flaw on the film, image data accurately reflecting an image on the film cannot be obtained. Therefore, Japanese Patent Application Laid-Open No. 9-16
Japanese Patent No. 3133 discloses a method of detecting the position of a flaw on a film and interpolating an image of the flaw position by an image processing unit based on surrounding pixels to eliminate the influence of the flaw.

[0003]

SUMMARY OF THE INVENTION The above-mentioned Japanese Patent Laid-Open No. 9-1
No. 63133 judges the position of a flaw on a film by using a dark-field optical system as a method of flaw detection to capture the scattered light from the flaw part. It is effective against foreign substances on the film (dust, matting agent for improving the slip of the film, etc.), but is low in effect. Further, there is no description about a specific detection method for dust and matting agents. Further, since a plurality of optical systems for flaw detection and imaging are provided, the size of the apparatus is increased. On the other hand, there is a method in which flaw detection and imaging are performed by moving the light shielding plate in and out with one optical system. However, such a method requires two imagings, and is particularly required when sub-scanning is performed using a line CCD. It takes a considerable amount of time.

The present invention has been made in view of such a problem, and an object of the present invention is to be able to accurately and quickly detect a foreign matter on a transparent original with a simple configuration including a single optical system. An object of the present invention is to provide a transparent document image reading apparatus.

[0005]

According to a first aspect of the present invention, there is provided an image reading apparatus for a transparent original which reads an image on a transparent original as image data corresponding to each pixel. Image storage means for storing image data read by the image reading means; and image data having a signal level corresponding to a predetermined range of the density of the transparent original among image data stored by the image storage means. And abnormal data detecting means for detecting as abnormal data.

According to a second aspect of the present invention, there is provided the image reading apparatus for a transparent original according to the first aspect, wherein the image reading means converts the image on the transparent original into a digital value of a plurality of colors. And the abnormal data detecting means detects the abnormal data based on digital values of one or more specific color densities among the digital values of the plurality of colors.

Further, according to a third aspect of the present invention, there is provided an image reading apparatus for a transparent original according to the first aspect of the present invention, wherein an abnormal data position for detecting a position on the transparent original corresponding to the abnormal data. Detecting means, and image processing means for replacing the abnormal data with image data obtained by performing an interpolation operation based on image data corresponding to a position around the position of the abnormal data detected by the abnormal data position detecting means. I do.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the outline of an embodiment of the present invention will be described. If foreign matter is on the negative film,
At the time of scanning, an image of a foreign substance is taken in simultaneously with the film image, which adversely affects the image quality. The foreign material mentioned here is, for example, dust or a matting agent. The matting agent is applied to the film in order to reduce the friction of the film surface, and is a particle having a diameter of about several μm.
If these foreign substances are imaged by a CCD having an opening approximately equal to or smaller than the size of the foreign substances, a "shadow" due to the foreign substances is selected, which eventually leads to deterioration of image quality.

Therefore, in the present embodiment, detection of a foreign substance is performed based on the following principle. Generally, the density of a negative film increases as the exposure amount increases. However, considering the exposure level of a normal scene, there is a difference between the maximum density level of the film and the dark level. On the other hand, the concentration of foreign matter on the film is higher than the highest concentration level of the film,
Close to the dark level. Therefore, when looking at a CCD output signal obtained by imaging a negative film with a foreign substance, a difference occurs between the original image signal level of the film and the signal level of the foreign substance. Therefore, if a predetermined threshold value is set between the levels, a film image and a foreign substance can be distinguished.

Further, looking at the spectral density of the negative film,
In general, the concentration is high on the short wavelength side (B side) and the concentration is high on the long wavelength side (R
Side) tends to be low. On the other hand, foreign substances on the film, such as dust and matting agent, block the illumination light, so that the density increases regardless of the wavelength range. Therefore, the difference between the original image signal level of the film and the signal level of the foreign matter is small on the short wavelength side and large on the long wavelength side. From this, RG of CCD
By performing foreign object detection using the R channel in the B channel, detection accuracy can be improved. Also,
Among the RGB channels of the CCD, a channel other than the R channel can be used, or a plurality of channels can be used together.

Hereinafter, the outline described above will be specifically described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of the first embodiment of the present invention. This film scanner comprises an image reading means 1 for reading an image on a negative film, and a frame memory 2 as an image storage means for temporarily storing the image read by the image reading means 1 as image data.
And a foreign matter detecting means 3 for detecting the position (coordinates) of a foreign matter (dust or a matting agent for improving the sliding of the film) on the film based on the image data stored in the frame memory 2. Interpolate pixel data corresponding to the foreign object using peripheral pixel data based on the position information of the foreign object,
And image processing means 4 for eliminating image noise due to foreign matter.

The above-described image reading means 1 includes a CCD 1d. CCD1d is a so-called line sensor, RG
B three lines are provided. Here, in order to read a two-dimensional image using a line sensor, an image is taken while scanning the negative film 1b through the lens 1c in the sub-scanning direction indicated by the arrow. Output signals (R, G, and B channels) from the CCD 1d are amplified by an amplifier 1e and quantized to digital values by an AD converter (ADC) 1f. ADC1f used here is a 12-bit ADC and Vre
From f-, Vref + can be quantized at 4096 gradations. The quantized data is standardized so that RGB is 0 for optical black (OB) and 4095 is light source direct view (transmittance 100%). The quantized digital values are sequentially stored in the frame memory 2, and at the end of the sub-scan, image data for a film-frame is accumulated.

The foreign substance detecting means 3 comprises a foreign substance detecting section 3a and a foreign substance coordinate memory 3b. The foreign object detector 3a reads out the R data of each pixel from the image data stored in the frame memory 2 and detects the position (coordinate) of the foreign object. The detected coordinates of the foreign object are sequentially stored in the foreign object coordinate memory 3b. You. Details of the method for detecting foreign matter will be described later.

The image processing means 4 comprises an interpolation operation section 4a and a gradation conversion section 4b. The interpolation calculation unit 4a performs image processing on the image data stored in the frame memory 2 based on the foreign object coordinate information stored in the foreign object coordinate memory 3b. That is, the image data (abnormal data) of the coordinates determined to be a foreign object by the foreign object detection unit 3a is subjected to an interpolation operation using the image data of the surroundings to replace the data, thereby eliminating the influence of the foreign object. The image data from which the influence of the foreign matter has been eliminated is subjected to processing such as negative-positive inversion and gamma conversion by the gradation conversion unit 4b, and becomes output data of the film scanner.

The method of interpolation calculation and the flow of processing in the above-described interpolation calculation unit 4a will be described later in detail. FIG. 2 is a diagram for explaining the principle of foreign matter detection in the foreign matter detection means 3. FIG. 2 shows the AD when scanning the negative film 1b.
It is a figure showing an output of R channel among outputs of C1f. The left vertical axis shows the output value of ADC1f, where ADC1f is 12
Since it is a bit, it can take a quantized value of 0 to 4095. The right vertical axis is the density value of the film corresponding to the output value of ADC1f. Here, since the reference voltage of the ADC 1f is set to the OB level and the transmittance 100% (density 0) level, 0 of the ADC output value corresponds to the density ∞ and 4095 corresponds to the density 0.

Although the density varies depending on the film, the R density of a negative film is generally distributed around 0.2 to 2.5, and when converted into the output value of the ADC 1f, 13 (=
Vmin) to 2580 (= Vmax). On the other hand, if there is a foreign matter on the negative film 1b, the illumination light is blocked by the foreign matter, and the ADC output value (= Vdust) at that portion becomes lower than the original R density distribution of the negative film 1b (V
(dust <Vmin). Therefore, an image having an output value equal to or more than Vmin with Vmin as a threshold value is a film image,
Foreign matter detection is performed by determining an image having a value less than Vmin as a foreign matter.

FIG. 3 is a diagram showing a processing flow of the foreign matter detecting section 3a. First, one pixel of R data R (x, y) is read from the frame memory 2 (step S1). Here, (x, y) is the coordinates of the pixel. Next, R (x,
y) and a threshold value Rmin (step S2), and R
If (x, y) <Rmin, FLAG (x, y) =
1, (step S3), otherwise FLAG (x,
y) = 0 is set (step S4). In other words, FLA
When G (x, y) = 1, the pixel at the coordinates (x, y) can be identified as a foreign substance. Next, FLAG (x,
y) is written into the foreign object coordinate memory 3b (step S5).
The above processing is performed for all the pixels stored in the frame memory 2, and the processing is terminated (step S6).

FIG. 4 is a diagram showing a processing flow of the interpolation operation section 4a. First, the RG for one pixel is read from the frame memory 2.
The B data is read (step S11). Subsequently, FLAG (x, y) is read from the foreign object coordinate memory 3b (step S12). Next, it is determined whether or not FLAG (x, y) = 1 (step S13), and FLAG (x, y) =
In the case of 1, R (x, y), G (x, y), B (x, y)
y) is subjected to a predetermined median filter (step S14), and if FLAG (x, y) = 0, step S14 is skipped. The above processing is performed for all the pixels stored in the frame memory, and the processing ends (step S15).

The median filter used here adopts, as interpolation data, pixel data having an intermediate value among a predetermined number of pixels around a pixel to be interpolated, and the value of the peripheral pixel as dust. This is effective when interpolating a pixel greatly deviating from.

Hereinafter, a second embodiment of the present invention will be described. FIG. 5 is a block diagram showing the configuration of the second embodiment of the present invention. The process from imaging by the CCD 1d to transfer to the frame memory 2 is the same as in the first embodiment, and a description thereof will be omitted. The image data stored in the frame memory 2 is sent to a negative / positive determination unit 7 where it is determined whether the film taken is negative or positive. PC 1 with monitor 15
6 is provided with a user interface for performing image display and various settings described later. The user can check and operate images on the monitor 15 via the interface (I / F) 14.

The gradation conversion section 8 converts the gradation of the image data from the frame memory 2 or the interpolation calculation section 9 in accordance with the type of film determined by the negative / positive determination section 7.
The foreign matter detection unit 11 determines the position of a foreign matter or a flaw in the image using the data of the frame memory 2, and stores the coordinates in the foreign matter coordinate memory 10. The EEPROM 13 stores a plurality of threshold values used for the judgment by the foreign object detection unit 11.

The data structure of the EEPROM 13 is as shown in FIG. The address is a memory address of the EEPROM 13 and has two words 00H and 01H (the address is in word units). The positive threshold value and the negative threshold value are threshold values used for a film and a negative, respectively. The threshold value setting unit 12 reads a threshold value from the EEPROM 13 based on the determination result of the negative / positive determination unit 7 and transfers the threshold value to the foreign substance detection unit 11. Also,
When the user instructs to change the threshold from the PC 16, the value is sent to the foreign object detection unit 11, and at the same time, the EEPR
Stored in the OM 13. The processing performed by the interpolation calculation unit 9 is the same as that of the first embodiment.

The overall processing flow will be described with reference to FIG. FIG. 8 shows a monitor 1 as a user interface.
5 is an initial screen. User reads “image” 15
a, "change threshold" 15b, "area designation" 15c,
Four types of designation of “application of processing” 15d can be performed. Here, the image reading process starts when the user instructs “image reading” 15a by clicking or the like (step S20). First, a film image including a foreign substance or a scratch is captured by the CCD 1d, the foreign substance is detected in accordance with the type of the film, and then the image is displayed (FIG. 9). As shown by, the image of the foreign matter portion is displayed blinking, and the user can recognize the detection result on the image.

In this display state, the user instructs "change threshold value" 15b (step S21), or
It is determined whether or not "area designation" 15c is instructed (step S23). If "threshold change" 15b is instructed, foreign matter detection is performed based on the changed threshold and an image is displayed. Is done. When the "area designation" 15c is instructed, foreign matter and flaw coordinate information are changed (step S25). Next, when the user instructs "application of processing" 15d (step S24), predetermined interpolation processing is performed (step S26), and the processing ends.

In response to the instruction of "change threshold value" 15b (step S21), the threshold value is changed (step S2).
After performing 2), when the "area designation" 15c is subsequently instructed (step S23), the change of the foreign matter and flaw coordinate information is subsequently performed (step S25). If the "application of processing" 15d is instructed without performing any of the "change threshold" 15b or the "area designation" 15c (step S24), a predetermined interpolation process is performed (step S26). ),finish.

Next, the details of the "image reading" 15a and "processing application" 15d will be described with reference to FIG. First, a film image including a foreign substance or a scratch is captured by the CCD 1d (step S30), and data is stored in the frame memory 2. Next, the negative / positive determination unit 7 analyzes the image data and determines whether the film taken is negative or positive (step S31). Usually, negative films have an orange base,
Negative / positive can be determined based on the ratio of the R, G, and B signals of the image data. The result of the determination is sent to the threshold value setting unit 12 and used for setting the threshold value. Specifically, the value stored at address 00H of the EEPROM 13 when it is determined to be positive, and the address 0 when it is negative.
The value stored in 1H is read and transferred to the foreign substance detection unit 11. The foreign matter detection unit 11 determines the coordinates of the foreign matter using the threshold value set by the threshold value setting unit 12,
The coordinate information is stored in the foreign object coordinate memory 10 (step S
33). The method of determining foreign matter and foreign matter coordinate information are the same as in the first embodiment.

Next, the negative / positive information is also sent to the tone converter 8, where tone conversion is performed on the image data in accordance with the type of the film, and is transferred to the PC 16 via the I / F 14. Further, the foreign object coordinate information stored in the foreign object coordinate memory 10 is also transferred to the PC 16 via the I / F 14. PC1
6 is displayed on the monitor 15 (step S34). Among the image data, the image data of the coordinates determined to be a foreign substance is blinkingly displayed (step S35), and is displayed separately from the other image data. You. Here, it is determined whether or not the user has instructed the "application of processing" 15d (step S36). In the case of YES, a predetermined interpolation operation is performed by the interpolation operation unit 9 and the gradation conversion unit 8 performs the predetermined interpolation operation. After gradation conversion is performed, the image is transferred to the PC 16 and displayed. Also,
If NO in step S36, the process ends without performing any image processing.

Next, the details of the above-mentioned "change threshold" 15b will be described. User changes "Threshold" 15
When "b" is designated, a threshold change dialog 17 as shown in FIG. 13 is displayed immediately. Here, the user inputs a threshold value in the input area 18 and an “OK” button 19
Is pressed, the input threshold value is changed from PC16 to I / F1.
4 to the threshold setting unit 12. The threshold value setting unit 12 changes the threshold value used for foreign matter determination in the foreign matter detection unit 11, and at the same time, writes the threshold value into the EEPROM 13 at an address corresponding to the film. Subsequently, the foreign matter detection unit 11 determines whether a foreign matter or a scratch is made using the new threshold value, and the image data determined to be foreign matter is blinked and displayed separately from the other image data. Here, when the user gives an instruction of “application of processing” 15 d, a predetermined interpolation calculation is performed by the interpolation calculation unit 9, the gradation conversion is performed by the gradation conversion unit 8, and the result is transferred to the PC 16 and displayed.

Next, the processing of the above-mentioned "area designation" 15c will be described in detail. When the user drags outward with the cursor around the foreign matter or scratch portion 15e in the designated image, the portion 15e is surrounded by a dotted area 15f as shown in FIG. In this state, when "area designation" 15c is designated, the coordinate information of the area becomes I / F
It is sent to the foreign matter detection unit 11 via. Foreign object detector 1
In step 1, image data only in the area is read from the frame memory 2 using the information, and a process for judging foreign matter is performed. Foreign object coordinate information FLAG (x, y) outside the area is all set to 0, and F is determined based on information determined only within the area.
LAG (x, y) = 0 or 1 is set in the foreign object coordinate memory 10. Here, the user applies “processing” 1
When the instruction of 5d is issued, the interpolation calculation using the updated foreign matter and flaw coordinate information is performed by the interpolation calculation unit 9, the gradation conversion is performed by the gradation conversion unit 8, and the result is transferred to the PC 16 and displayed. FIG.
Reference numeral 2 denotes a display state after the interpolation processing has been performed.

According to the above-described second embodiment, (1) the user can manually change the threshold value for judging a foreign substance or a flaw. You can respond while checking the image. (2) Although the threshold value differs greatly between the negative and the positive due to the characteristics of the film, by changing the threshold between the negative and the positive, the negative and the positive can be used without being conscious of the negative and the positive. (3) By specifying an area, processing can be performed only on a foreign substance or a damaged part, so that erroneous processing due to erroneous determination in other areas can be prevented. Further, since the processing is performed only in the area, the processing can be performed at high speed. (4) Since the detected foreign matter is displayed blinking, it is easy to distinguish it from other images, and the result of the processing is easy to understand by comparing it with that after processing.

The specific embodiments described above include inventions having the following configurations. [Additional Item 1] In a transparent original image reading apparatus that reads an image on a transparent original as image data corresponding to each pixel and detects a foreign substance on the transparent original based on the image data, An image reading apparatus for a transparent original, wherein image data having a signal level corresponding to a density of the transparent original that is equal to or higher than a predetermined value is detected as foreign object image data that recognizes foreign matter on the transparent original.

[Additional Item 2] The read image data is obtained by reading an image on a transparent original as digital values of a plurality of colors, and the foreign object image data is a red color image of the digital values of the plurality of colors. 3. The image reading apparatus for a transparent original according to claim 1, wherein the image data is image data detected based on a digital value of density.

[Additional Item 3] The position of the foreign matter on the transparent document corresponding to the foreign matter image data is detected, and the foreign matter image data is obtained by interpolation based on the image data corresponding to the peripheral position of the foreign matter. 3. The image reading apparatus for a transparent original according to claim 1, wherein the influence of foreign matter on the transparent original is eliminated by replacing with image data.

[Appendix 4] Image reading means for reading an image on a transparent original as image data corresponding to each pixel,
Image storage means for storing the image data read by the image reading means; and image data having a signal level corresponding to the density of the transparent original of a predetermined value or more among the image data stored by the image storage means. Foreign matter detecting means for detecting foreign matter on a document as foreign matter image data recognizing the foreign matter; foreign matter position detecting means for detecting the position of a foreign matter on a transparent document corresponding to the foreign matter image data detected by the foreign matter detecting means; By replacing the image data with image data obtained by performing an interpolation operation based on the image data corresponding to the periphery of the position of the foreign matter detected by the foreign matter position detecting means, the influence of the foreign matter on the transparent original is eliminated. Image processing means, and image display means for displaying an image on a transparent document based on an output signal from the image processing means;
An image reading apparatus for a transparent original, comprising:

[Appendix 5] Transparent original detecting means for detecting the type of transparent original, signal level storing means for storing each predetermined signal level corresponding to the density of the transparent original according to the type of transparent original, A predetermined signal level corresponding to the density of the transmitted original stored in the signal level storage is read out based on the detection result of the original detecting means, and this signal level is corresponded to the density of the transmitted original equal to or higher than the predetermined value in the foreign matter detecting means. Signal level setting means for setting a signal level to be set as the signal level to be set, wherein the foreign substance detection means converts the image data having the signal level set by the signal level setting means to a foreign substance on a transparent original document. 5. The image reading apparatus for a transparent document according to claim 4, wherein the image is detected as data.

[Appendix 6] The image reading means reads the image on the transparent document as digital values of a plurality of colors, and the foreign matter detecting means detects the digital value of the plurality of colors based on the digital value of red density. 5. The image reading apparatus for a transparent document according to claim 4, wherein foreign matter image data is detected.

[Additional Item 7] The image reading apparatus for a transparent original according to Additional Item 4, wherein the image display means displays the foreign matter in distinction from other images to be displayed. [Appendix 8] Transparent original detecting means for detecting the type of transparent original, signal level storing means for storing each predetermined signal level corresponding to the density of the transparent original according to the type of transparent original, and signal level storing means And a signal level changing means for changing a predetermined signal level corresponding to the density of the transmitted original stored by the signal processing means, and a predetermined level of the signal level storing means changed by the signal level changing means based on a detection result of the transparent original detecting means. Signal level setting means for setting the signal level as a signal level corresponding to the density of the transmitted original of a predetermined value or more in the foreign matter detecting means. The image data having the signal level set by the setting means is detected as foreign object image data which recognizes a foreign object on a transparent original. 5. The image reading apparatus for transparent originals according to claim 4, wherein

[Appendix 9] The image display device further comprises an area designating means for designating a predetermined area on the image displayed on the image display means, and the foreign matter detecting means is provided only for the predetermined area designated by the area designating means. 5. The image reading apparatus for a transparent document according to any one of items 4, 5 and 8, wherein the image reading is performed.

[Supplementary Item 10] The transparent document detecting means according to any one of Additional Items 5 and 8, wherein the transparent document detecting means detects whether the transparent document is a negative transparent document or a positive transparent document. Image reader for transparent documents.

[Appendix 11] Image reading means for reading an image on a transparent original as image data corresponding to each pixel, image storage means for storing image data read by the image reading means, and image storage means Abnormal data detecting means for detecting, as abnormal data, image data having a signal level corresponding to the density of the transparent original in a predetermined range among the image data stored by The above image is read as a digital value of a plurality of colors, and the abnormal data detecting means detects the abnormal data based on a digital value of a single or a plurality of specific color densities among the digital values of the plurality of colors, The image reading apparatus for a transparent document, wherein the specific color density is a red density.

[0041]

According to the present invention, foreign matter detection is performed by utilizing the density difference between the film image and the foreign matter on the film, so that it is not necessary to use a special optical system for foreign matter detection, and the apparatus can be miniaturized. Becomes possible. At the same time, it is not necessary to take an image only for the purpose of foreign substance detection, so that the processing time can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a first exemplary embodiment of the present invention.

FIG. 2 is a diagram for explaining the principle of foreign matter detection in the foreign matter detection means 3;

FIG. 3 is a diagram showing a processing flow of a foreign object detection unit 3a.

FIG. 4 is a diagram showing a processing flow of an interpolation calculation unit 4a.

FIG. 5 is a block diagram showing a configuration of a second embodiment of the present invention.

FIG. 6 is a diagram showing a data structure of an EEPROM 13;

FIG. 7 is a flowchart for explaining the overall processing flow of the second embodiment.

FIG. 8 is a diagram showing an initial screen of the monitor 15;

FIG. 9 is a diagram showing a display on a monitor after foreign object detection is performed.

FIG. 10 shows “image reading” 15a and “processing application” 1
It is a flowchart which shows the detail of a process of 5d.

FIG. 11 is a diagram showing how an area is designated by a user.

FIG. 12 is a diagram showing a display on a monitor after performing an interpolation process.

FIG. 13 is a diagram showing a state where a threshold change dialog is displayed on the monitor 15;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Image reading means, 1a ... Light source, 1b ... Negative film, 1c ... Lens, 1d ... CCD, 1e ... Amplifier, 1f ... ADC, 2 ... Frame memory, 3 ... Foreign substance detection means, 3a ... Foreign substance detection part, 3b ... Foreign object coordinate memory, 4 ... image processing means, 4a ... interpolation operation unit, 4b ... gradation conversion unit

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI H04N 1/00 G06F 15/64 325J

Claims (3)

[Claims] 1. An image reading means for reading an image on a transparent document as image data corresponding to each pixel, an image storage means for storing image data read by the image reading means, and an image storage means for storing the image data. Of the image data
A transmission document image reading device, comprising: abnormal data detection means for detecting, as abnormal data, image data having a signal level corresponding to the density of the transmission document in a predetermined range. 2. The image reading means reads an image on a transparent original as digital values of a plurality of colors, and the abnormal data detecting means reads a digital value of one or more specific color densities of the digital values of the plurality of colors. 2. The image reading apparatus for a transparent original according to claim 1, wherein the abnormal data is detected based on the following. 3. An abnormal data position detecting means for detecting a position on the transparent document corresponding to the abnormal data, and an image corresponding to the vicinity of the position of the abnormal data detected by the abnormal data position detecting means. 2. The image reading apparatus for a transparent original according to claim 1, further comprising: image processing means for replacing image data obtained by performing an interpolation operation based on the data.